A research on proximity communication between devices is being performed by the 3rd Generation Partnership Project (3GPP) at present. As its main application scenario, when there is a short distance between two devices in communication with each other, an application layer data transmission may be performed directly between the two devices rather than through a mobile communication network, or forwarded by a serving base station connected to the devices rather than through a core network. For this purpose, it is required to study how the application layer can trigger a network layer to find a proximity relation and establish the proximity communication, and how an application layer user service identifier (ID) can be associated with a network layer identifier.
FIG. 1 shows a data channel for the communication between two devices defined in 3GPP. The data is transmitted by a User Equipment 1 (UE1) to a serving evolved Node B (eNB), and then transmitted by the eNB to a Serving Gate-Way (SGW) and a Packet Data Network Gate-Way (PGW) of a serving core network. Next, in accordance with a routing table of UE, the data is routed by the PGW to a serving PGW and a Serving GW of the UE1, and transmitted by the Serving GW of a UE2 to a serving eNB of the UE2, and then transmitted to the UE2 by the eNB. In the example shown in FIG. 1, the Serving GW and PGW of UE1 is identical to that of UE2, and a process of routing the data to the PGW served for UE2 from the PGW served for UE is omitted.
As can be seen from FIG. 1, even when there is a very short distance between the two devices in communication with each other, it is still required to transmit the data from one to another through the serving eNBs and the core network, which thus results in a large communication delay as well as additional network resource usage. Hence, a communication technique for proximal devices is being studied by the 3GPP, so as to achieve the communication directly between two UEs or merely by means of the eNB when there is a very short distance between two UEs.
FIGS. 2a and 2b show data transmission paths between two terminals after the proximity communication is implemented. As shown in FIGS. 2a and 2b, the data may be transmitted directly between the UE1 and UE2 rather than through a mobile network device, or when two UEs are connected to an identical eNB, the data may be forwarded through this serving eNB rather than through the core network. Through this transmission mode, it is able to reduce the delay for the data transmission, and save the network resources, especially the resources of the core network.
Requirements for the proximity communication are being discussed in 3GPP SA1. On the basis of the results of the discussion, generally there are two problems in the proximity communication. i.e., how to discover the proximity relation between the terminals, and how the proximal UEs can communicate with each other directly.
The discovery process for the proximity relation between the terminals is a prerequisite to the direct communication between the proximal terminals, and meanwhile it may be applied in various scenarios. For example, a shop may, through detecting the proximity relation, send discounting or promoting advertisements to the terminals held by passersby, a user may search information about restaurants and supermarkets in proximity to a current position on the basis of a proximity relation discovery function, and a bus stop may forecast bus arrival information on the basis of the proximity relation discovery function.
Such direction communication between the UEs still needs to be controlled through a network, and the resources for a proximity communication service (ProSe) are determined by the network. Hence, information interaction will also occur between the serving eNB of the UE and a Mobile Management Entity (MME). When two UEs in the proximity communication reside in different eNBs, signaling interaction may also occur between the core network and these eNBs, respectively.
A scenario where the discovery of the proximity relation is restrained has been defined in the 3GPP. To be specific, when a service provider provides authorization for a certain service that it may use a proximity service feature and a user owns a terminal which is allowed to use the proximity service, he may discover his nearby friend who also owns a terminal with the same feature, and he may also be discovered by his friend.
The proximity service feature may also be used by a Social Network Service (SNS) application. For example, when a certain SNS application is used by Mary, Peter and John, the following relation information is displayed in the context maintained at its application layer: Mary and John are friends, John and Peter are friends, and Mary and Peter are not friends.
Presumed that Mary, Peter and John own the terminals with the proximity service feature, have subscribed to an identical cellular network service provider, and the service provider has authorized them to use the proximity service feature, the following functions need to be achieved in this scenario. Mary's UE may discover that John is at a proximal position, John's UE may discover that Mary is at a proximal position, Mary's SNS application can know whether or not John is at a proximal position. John's SNS application can know whether or not Mary is at a proximal position. Peter's UE cannot discover that Mary's UE is at a proximal position, Mary's SNS application cannot detect whether or not Peter is at a proximal position, and Peter's SNS application cannot detect whether or not Mary is at a proximal position.
Hence, it is required by this feature that merely the friends can discover the proximity relation, and when the users are not friends as displayed at the application layer, it is impossible for them to discover the proximity relation.
The proximity relation discovery feature between UEs may also be controlled by the service provider. For a UE with a proximity relation discovery function, the following features may be configured for the UE by strategy and user selection. It may discover the proximal UEs but cannot be discovered by the others, it may be discovered by the other UEs but cannot discover the others, it may discover the other UEs and can be discovered by the others, it cannot be discovered by the other UEs and cannot discover the others, or during the proximity relation discovery process, it may merely discover the UEs that have been set as being allowed to be discovered by the others.
Hence, in accordance with the present requirements on the proximity communication service defined by the 3GPP, the terminal is required to, when triggered by the application layer, initiate the proximity communication service including the discovery of the proximity relation and the establishment of the proximity communication connection. These requirements are related to such factors as proximity relation subscription information about the terminal, network configuration and user relation at the application layer. Due to the various applications on the terminal, there are various application layer identifiers, and it is impossible for a 3GPP network to associate all the application layer identifiers on the UE with the UE's 3GPP network layer identifiers. In addition, the application layer is independent of the network layer, and a user may log in a certain application on a terminal A or B, so it is difficult for the 3GPP network to maintain an association relationship between the user's application layer identifier and the UE's 3GPP network layer identifier.
Based on the above, when the application on the UE requires the use of the proximity communication service, including the discovery of the proximity relation and the establishment of the proximity communication connection, it is impossible for the network to determine the UE's 3GPP network layer identifier in accordance with the user's application layer identifier, so it is impossible to perform the proximity communication service.